Process for the preparation of manganese complexes of salen compounds

ABSTRACT

A process for the preparation of manganese complexes of salen compounds which comprises carrying out the reaction of a salen compound with a manganese compound in DMF is described. In a preferred embodiment, the salen compound itself is synthesised likewise in DMF and reacted without intermediate isolation to form the manganese complex.

The present invention relates to a process for the preparation ofmanganese complexes of salen compounds, to the compounds preparedaccording to that process, and to the use thereof in washing andcleaning solutions.

Manganese complexes of salen compounds are known, for example, fromEP-A-902 083 and EP-A-955 289. They are usually prepared from theappropriate salen ligands by reaction with a manganese salt in ethanolicsolution in the presence of air as oxidizing agent. The ligandsthemselves are obtained, for example, by reacting the appropriate di- ortri-amines with the appropriate o-hydroxyaldehydes in methanolic orethanolic solution and crystallising out the ligands. Since, however, onan industrial scale working in methanol or ethanol at elevatedtemperature in the presence of air necessitates complex safety measures,the need existed for an improved method of synthesis.

It has now been found, surprisingly, that the reaction of the ligandwith the manganese salt can advantageously be carried out indimethylformamide (DMF) as solvent, and at the same time it is possibleto operate at a temperature sufficiently far below the flash point ofthe solvent that even in the presence of air there are no safetyproblems. The preparation of the ligand can be carried out, for example,in water or, preferably, likewise in DMF. Surprisingly, it is evenpossible to carry out the synthesis of the ligand and the preparation ofthe manganese complex in DMF as a “one-pot reaction”, that is to saywithout isolation and purification of the ligand.

The present invention accordingly relates to a process for thepreparation of manganese complexes of salen compounds of formula

in which formulae

A is an anion;

n, m and p are each independently of the others 0, 1, 2 or 3,

R, R₁ and R₁′ are each independently of the others cyano; halogen; OR₄or COOR₄, wherein R₄ is hydrogen or linear or branched C₁-C₄alkyl;nitro; linear or branched C₁-C₈alkyl; linear or branched partiallyfluorinated or perfluorinated C₁-C₈alkyl; NR₅R₆, wherein R₅ and R₆ areidentical or different and are each independently of the other hydrogenor linear or branched C₁-C₁₂alkyl; or linear or branched C₁-C₈alkyl-R₇,wherein R₇ is a radical NH₂, OR₄, COOR₄ or NR₅R₆ as defined above; or—CH₂—N^(⊕)R₄R₆R₇ or —N^(⊕)R₄R₅R₆, wherein R₄, R₅ and R₆ are as definedabove,

R₂ and R₃ are each independently of the other hydrogen, linear orbranched C₁-C₄alkyl or unsubstituted aryl or aryl that is substituted bycyano; by halogen; by OR₄ or COOR₄, wherein R₄ is hydrogen or linear orbranched C₁-C₄alkyl; by nitro; by linear or branched C₁-C₈alkyl; by NHR₅or NR₅R₆, wherein R₅ and R₆ are identical or different and are eachhydrogen or linear or branched C₁-C₁₂alkyl or wherein R₅ and R₆ togetherwith the nitrogen atom linking them form a 5-, 6- or 7-membered ringthat may contain further hetero atoms; or by linear or branchedC₁-C₈alkyl-R₇, wherein R₇ is a radical NH₂, OR₄, COOR₄ or NR₅R₆ asdefined above; or by —N^(⊕)R₄R₅R₆, wherein R₄, R₅ and R₆ are as definedabove,

R₈ radicals are each independently of the others hydrogen or linear orbranched C₁-C₄alkyl,

Y is a linear or branched alkylene radical of formula —[C(R₄)₂]_(r)—,wherein r is an integer from 1 to 8 and the R₄ radicals are eachindependently of any other(s) as defined above; —CX═CX—, wherein X iscyano, linear or branched C₁-C₈alkyl or di(linear or branchedC₁-C₈alkyl)amino; —(CH₂)_(q)—NR₄—(CH₂)_(q)—, wherein R₄ is as definedabove and q is 1, 2, 3 or 4; or a 1,2-cyclohexylene radical of formula:

wherein R₉ is hydrogen, SO₃H, CH₂OH or CH₂NH₂,

wherein in formula (1) the phenyl rings may together carry no more thanthree tert-butyl substituents, and wherein, when Y is 2-hydroxypropyleneand m and n are each 0, R₂ and R₃ may not both be H, and wherein when Yis ethylene or o-phenylene and m and n are each 0 and MnO is used as themanganese compound, R₂ and R₃ may not both be H,

which process comprises reacting a ligand of formula

wherein R, R₁, R₁′, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Y, A, n, m and p areas defined for formulae (1), (2) and (3),

with a manganese compound in dimethylformamide as solvent.

In the compounds of formula (1) or (3) in which n, m or p is 2 or 3, theradicals R, R₁ and R₁′ have identical or different meanings. The sameapplies to compounds of formula (2) in respect of the R₈ radicals.

When Y is a 1,2-cyclohexylene radical, that radical may be in either ofits stereoisomeric cis/trans forms.

Preferably, Y is a radical of formula —(CH₂)_(r)— wherein r is aninteger from 1 to 8, or a radical of formula —C(R₅)₂—(CH₂)_(p)—C(R₅)₂—wherein p is a number from 0 to 6 and R₅ is hydrogen or C₁-C₄alkyl.

In especially preferred compounds of formulae (1) and (2), Y is aradical of formula —(CH₂)_(r)— wherein r is an integer from 1 to 4, or aradical of formula —(CR₅)₂—(CR₅)₂— wherein the R₅ radicals are eachindependently of the others hydrogen or methyl.

Halogen is preferably chlorine, bromine or fluorine, chlorine beingespecially preferred.

When R, R₁ or R₁′ is di(C₁-C₁₂alkyl)amino, the alkyl group may bestraight-chain or branched. Preferably it contains from 1 to 8,especially from 1 to 4, and more especially 1 or 2, carbon atoms.

Preferably, the radicals R, R₁ and R₁′ are hydrogen, nitro, OR₄, COOR₄or N(R₄)₂, wherein R₄ is hydrogen or C₁-C₄alkyl, especially methyl orethyl.

The radicals R₂ and R₃ are especially hydrogen, methyl, ethyl orunsubstituted phenyl.

Aryl is, for example, naphthyl or especially phenyl.

When R₅ and R₆ together with the nitrogen atom linking them is a 5-, 6-or 7-membered ring, that ring is especially a pyrrolidine, piperidine,morpholine or piperazine ring. The piperazine ring may be substituted,for example by alkyl, at the nitrogen atom that is not bonded to thephenyl radical.

Suitable anions include, for example, halide, for example chloride,perchlorate, sulfate, nitrate, hydroxide, BF₄ ⁻, PF₆ ⁻, carboxylate,acetate, tosylate and triflate. Of those, preference is given tochloride, acetate and carboxylate.

The ligands of formulae (4), (5) and (6) are known or can be prepared ina manner known per se.

In the process according to the invention, the reaction of those ligandswith a manganese compound is carried out in DMF at a temperature of fromapproximately 10° C. to the boiling point of DMF, but preferably at atemperature of from 20 to 70° C., especially from 20 to 40° C.

The manganese compounds used are especially manganese(II) salts,especially manganese(II) chloride, sulfate or acetate.

Preferably, the manganese compound is added in slight excess, especiallyan excess of from 0.5 to 3%.

During the reaction, preferably air, as oxidizing agent, is passedthrough the reaction mixture, but it is also possible to use otheroxidizing agents.

After the reaction, the manganese complex is isolated in a manner knownper se, for example by crystallising it out by the addition of sodiumchloride and then distilling off the DMF at elevated temperature invacuo, suspending the residue in water and filtering.

In an especially preferred embodiment of the process according to theinvention, the ligands used have not been formed and isolated beforehandbut instead the synthesis of the ligand and the reaction to form themanganese complex are carried out in DMF as a so-called one-potreaction.

The present invention accordingly relates also to a process for thepreparation of manganese complexes of the above formulae (1), (2) and(3) which comprises, in DMF as solvent, reacting a diamine of formula

H₂N—Y—NH₂  (7)

with an o-hydroxybenzaldehyde of formula

or reacting the compound of formula

N(—CH₂—CH₂—NH₂)₃  (10)

with an o-hydroxybenzaldehyde of formula (8), in which formulae R, R₂,R₈ and n are as defined for formulae (1) and (2), and then, withoutintermediate isolation, reacting the resulting salen compound with amanganese compound to form a manganese complex of formula (1), (2) or(3).

The first reaction is carried out at approximately from 10 to 40° C.,preferably at room temperature, and di- or tri-amine and aldehyde arepreferably used approximately in a molar ratio of 1:2 or 1:3,respectively.

The reaction conditions for the second step correspond to the conditionsdescribed above for the synthesis of the manganese complexes from ligandand manganese compound.

The manganese complexes are in that manner obtained with a good level ofpurity and a high yield according to a very simple process. They areused especially as catalysts that enhance the action of peroxy compoundsin washing, cleaning and disinfecting procedures.

The following Examples serve to illustrate the invention but do notlimit the invention thereto. Unless specified otherwise, parts andpercentages relate to weight.

EXAMPLE 1

12 kg of 4,4′-[1,2-ethanediylbis(nitrilomethylidyne)]bis-1,3-benzenedioland 115 kg of N,N-dimethylformamide are introduced into a vessel. Withvigorous stirring, 9.9 kg of manganese(II) acetate×4H₂O are introducedinto the yellow suspension. Using a submerged tube, 10 litres of air perminute are passed through the reaction mixture, in the course of whichthe mixture is heated to 30° C., and that temperature is maintained for2 hours. When the reaction is complete, 26 kg of sodium chloride areadded, as a result of which the manganese complex crystallises out. TheDMF is removed from the reaction mixture by distillation at 50 mbar at atemperature of from 65 to 77° C. 120 litres of water are added to theresidue and the resulting brown suspension is cooled to roomtemperature. A further 2 kg of sodium chloride are then added and thereaction mixture is stirred for a further 30 minutes and then filtered.The residue is washed with 10% sodium chloride solution.

The filter cake is then dried for 24 hours at 100° C. in vacuo. 15 kg ofproduct of formula

having a high level of purity are obtained.

EXAMPLE 2

69 g of 2,4-dihydroxybenzaldehyde are introduced into a 1 litre,double-walled ground-necked flask and 750 ml of DMF are added thereto.At room temperature, 15 g of ethylenediamine are then added in thecourse of 5 minutes and the mixture is subsequently stirred forapproximately a further 15 minutes, the temperature rising toapproximately 30° C. Using a gas inlet tube and a rotameter, 5 l/min ofair are introduced and at 30° C. 61.8 g of manganese(II) acetatetetrahydrate are added. After 1 hour, 200 g of sodium chloride are addedand stirring is carried out for a further 1 hour until ligand can nolonger be detected by thin-layer chromatography.

The DMF is then distilled off from the reaction mixture at 60° C. and 30mbar. The resulting brown residue is cooled to 50° C. and suspended in750 ml of water. The resulting brown suspension is cooled to 20° C.,stirred for a further 30 minutes and filtered. The filter cake is washedwith 10% sodium chloride solution and then dried in vacuo at 75° C.

92.0 g of manganese complex of the formula given in Example 1 areobtained in a high level of purity.

What is claimed is:
 1. A process for the preparation of a manganesecomplex of salen compounds of formula

in which formulae A is an anion; n, m and p are each independently ofthe others 0, 1, 2 or 3, R, R₁ and R₁′ are each independently of theothers cyano; halogen; OR₄ or COOR₄, wherein R₄ is hydrogen or linear orbranched C₁-C₄alkyl; nitro; linear or branched C₁-C₈alkyl; linear orbranched partially fluorinated or pertfluorinated C₁-C₈alkyl; NR₅R₆,wherein R₅ and R₆ are identical or different and are each independentlyof the other hydrogen or linear or branched C₁-C₁₂alkyl; or linear orbranched C₁-C₈alkyl-R₇, wherein R₇ is a radical NH₂, OR₄, COOR₄ or NR₅R₆as defined above; or -CH₂—N^(⊕)R₄R₆R₇ or —N^(⊕)R₄R₅R₈, wherein R.₄, R₅and R₆ are as defined above, R₂ and R₃ are each independently of theother hydrogen, linear or branched C₁-C₄alkyl or unsubstituted aryl oraryl that is substituted by cyano; by halogen; by OR₄ or COOR₄, whereinR₄ is hydrogen or linear or branched C₁-C₄alkyl; by nitro; by linear orbranched C₁-C₈alkyl; by NHR₅ or NR₅R₆, wherein R₅ and R₆ are identicalor different and are each hydrogen or linear or branched C₁-C₁₂alkyl orwherein R₅ and R₆ together with the nitrogen atom linking them form a5-, 6- or 7-membered ring that may contain further hetero atoms; or bylinear or branched C₁-C₈alkyl-R₇, wherein R₇ is a radical NH₂, OR₄,COOR₄ or NR₅R₆ as defined above; or by —N^(⊕)R₄R₅R₆, wherein R₄, R₅ andR₆ are as defined above, R₈ radicals are each independently of theothers hydrogen or linear or branched C₁-C₄alkyl, Y is a linear orbranched alkylene radical of formula —[C(R₄)₂]_(r)—, wherein r is aninteger from 1 to 8 and the R₄ radicals are each independently of anyother(s) as defined above; —CX═CX—, wherein X is cyano, linear orbranched C₁-C₈alkyl or di(linear or branched C₁-C₈alkyl)amino;—(CH₂)_(q)—NR₄—(CH₂)_(q)—, wherein R₄ is as defined above and q is 1, 2,3 or 4; or a 1,2-cyclohexylene radical of formula:

wherein R₉ is hydrogen, SO₃H, CH₂OH or CH₂NH₂, wherein in formula (1)the phenyl rings may together carry no more than three tert-butylsubstituents, and wherein, when Y is 2-hydroxypropylene and m and n areeach 0, R₂ and R₃ may not both be H, which comprises reacting a ligandof formula

wherein R, R₁, R₁′, R₂, R₃, R₄, R₅, R₆, R₇, R₈, R₉, Y, A, n, m and p areas defined for formulae (1), (2) and (3), with a manganese(II) salt indimethylformamide as solvent.
 2. A process according to claim 1, whereinthe synthesis of the ligand and the reaction to form the manganesecomplex are carried out in dimethylformamide in a one-pot reaction.
 3. Aprocess according to claim 1, which comprises reacting, indimethylformamide as solvent, a diamine of formula H₂N—Y—NH₂  (7) withan o-hydroxybenzaldehyde of formula

or reacting the compound of formula N(—CH₂—CH₂—NH₂)₃  (10) with ano-hydroxybenzaldehyde of formula (8), in which formulae Y, R, R₂, R₉ andn are as defined for formulae (1) and (2) in claim 1, and then, withoutintermediate isolation, reacting the resulting salen compound with amanganese(II) salt to form a manganese complex of formula (1), (2) or(3).
 4. A process according to claim 1, wherein Y is a radical offormula —(CH₂)_(r)— wherein r is an integer from 1 to 8, or a radical offormula —C(R₅)₂—(CH₂)_(p)—C(R₅)₂— wherein p is a number from 0 to 6 andR₅ is hydrogen or C₁-C₄alkyl.
 5. A process according to claim 1, whereinR, R₁ and R₁′ are hydrogen, nitro, OR₄, COOR₄ or N(R₄)₂, wherein R₄ ishydrogen or C₁-C₄alkyl.
 6. A process according to claim 1, wherein R₂and R₃ are hydrogen, methyl, ethyl or unsubstituted phenyl.
 7. A processaccording to claim 1, which is carried out at a temperature of fromapproximately 20 to 70° C.
 8. A process according to claim 1, whereinthe manganese compound is added in an excess of from 0.5 to 3%.
 9. Aprocess according to claim 3, wherein the first reaction is carried outat approximately from 10 to 40° C., and the di- or tri-amine andaldehyde are used approximately in a molar ratio of 1:2 or 1:3.